Persons acquainted with the operation of upwardly acting doors having an electrical operator for effecting door movement are aware that some door operators have a safety switch whereby the direction of door movement is automatically reversed if the door engages an obstruction during movement in its downward or closing direction. This safety feature, as disclosed in U.S. Pat. No. 3,474,317 owned by the assignee of this application, has been provided to prevent damage to equipment and injury to personnel which might result from continued operation of the door. While operators of this type have been commercially acceptable, nevertheless they do possess structural and operational features which have been undesirable either from a cost, maintenance or operational viewpoint.
To improve upon operators of this type, U.S. Pat. No. 3,764,875 discloses an operator having a mechanical override system for deactivating the safety switch when the door is within a preselected distance from either its fully opened or fully closed position to prevent reversal of the door movement. While the operator of this patent does possess the ability to deactivate the safety switch, nevertheless this operator is structurally complex and does not possess the degree of flexibility necessary to provide for optimum control over all of the door movements.
Accordingly, the objects and purposes of the invention have been met by providing a motorized door operator having improved switch mechanism and circuitry capable of overcoming the problems and achieving the results set forth above.
A further object of the invention is the provision of a door operator, as aforesaid, which represents a substantial improvement, both structurally and operationally, over the operators disclosed in the patents mentioned above.
A still further object of the invention is the provision of a door operator, as aforesaid, which is fool proof in operation, simple in construction, can be adapted to existing door operating mechanisms, and does not interfere with the normal manual or remote control conventionally utilized for energizing the electrical system.
Still a further object of the invention is the provision of a door operator, as aforesaid, which possesses (1) a reversing safety switch for automatically causing upward movement of the door when the door strikes an obstruction during the downward movement thereof, (2) up and down limit switches for deactivating the operator when the door respectively reaches its fully opened and fully closed positions, and (3) up and down cut-off switches for overriding the safety switch when the door is within a preselected distance from its respective fully opened and fully closed position.
Another object of the invention is the provision of a door operator, as aforesaid, which incorporates a slide assembly within the switch mechanism for controlling the limit and cut-off switches in a simple yet reliable manner.
Other objects and purposes of this invention will be apparent to persons familiar with this type of equipment upon reading the following specification and inspecting the accompanying drawings.